SmogRank / History / Country race
Countries, worst air first, day by day
Each country's typical measured city over the 30 days to every day since January 2023, worst first. Press Play to watch the order change, or drag the slider to any day.
The worst countries for PM2.5 over the 30 days to 18 Jul 2025: Chile 53.9 µg/m³, Pakistan 38.5 µg/m³ and Peru 27.7 µg/m³.
- 1Chile47 cities53.9
- 2Pakistan11 cities38.5
- 3Peru5 cities27.7
- 4India210 cities21.1
- 5Mexico38 cities13.2
- 6New Zealand10 cities13.1
- 7Japan566 cities12.9
- 8South Korea140 cities12.2
- 9Martinique3 cities11.7
- 10Italy22 cities, was 2011.6
- 11Malta4 cities11.1
- 12Bosnia and Herzegovina5 cities10.4
- 13Slovakia41 cities10.1
- 14Spain112 cities, was 879.4
- 15Greece7 cities9.1
- 16Hungary10 cities, was 128.9
- 17Canada117 cities8.4
- 18Romania11 cities8.3
- 19United States841 cities8.2
- 20Hong Kong13 cities7.8
+ 20 more countries, 7.8 µg/m³ and below
Not counted on this day, too few cities measured: Serbia since 10 Jul 2025, Thailand since 10 Jul 2025, Taiwan since 10 Jul 2025 and Laos since 8 Jun 2025.
Countries counted each day
A country's number is its typical measured city: the median of its cities' means over the 30 days (a city needs 21 of them measured; 5 of 7 on the 7-day race), shown only with 3 such cities. A country whose monitors go quiet fades out where it stood rather than sliding down, so a gap never reads as cleaner air; "was" beside a city count marks a month after many cities joined or left. Some large countries are thin or missing because their monitors' licences don't allow reuse. How we rank.
Not covered: the government monitoring networks of China and Turkey, which publish only on their own websites; we are building the readers for them. Most cities there are missing from this board, not clean. Why.